That is an expensive case. "Servers" are only small for when they go into datacenters and they need to fit as many as possible into a confined space.
You can use any case, any decent PSU, any decent motherboard, etc. It is literally just a PC that you use for "Serving" which could be doing anything.
For just a minecraft server, I would just buy an offlease Dell/Lenovo desktop with a decent chunk of memory or a refurb.
If you are going to build some, build yourself a gaming PC and use your current machine as a server.
alright thanks for the info, and for the gaming PC i have one. thats the one i use to play steam and other stuff. The macbook pro is my moms old laptop that she is thinking of selling so i don't want to make plans on using it. Ill think ill either try to find an old desktop or laptop for cheap and use that, like you suggested.